In the UK, all current on-road trials of AVs include a safety driver or safety operator. This is a trained person whose role is to mitigate the risk associated with testing a prototype vehicle. Situations when they will be intended to intervene include:
- Conditions outside the vehicle’s Operational Design Domain (ODD)
- System failures affecting the driving task
- Incorrect actions by the automated driving system (ADS)
It is generally expected that AVs will be designed to come to a controlled stop when they exit their ODD or suffer a system failure. The process of coming to this stop and the stopped state are termed ‘Minimal Risk Manoeuvre’ (MRM) and ‘Minimal Risk Condition’ (MRC) respectively. For convenience, we term the combination of these ‘MRX’.
Automated MRX functionality can address the first two of the safety driver’s responsibilities listed above. This means evidence of suitable MRX functionality is expected to form a vital part of the safety case for operation without a safety driver. Different methods are required to manage the risk posed by the ADS making incorrect actions in nominal operation, which is outside the scope of this project.
The aims of the SafeMRX project are to:
- Help ADS developers and operators understand how MRX safety should be engineered and documented in their safety case.
- Help assurers determine if an ADS safety case is sufficient to demonstrate MRX safety
- Provide a foundation to be built on by future standards or regulations covering MRX behaviour
The project does not explicitly consider trials or deployments where there is a safety driver present in the vehicle, although many of the project outputs will still be relevant.